Access networks are presently experiencing rapid growth around the world. Both residential and business customers are demanding increasingly higher bandwidths from their Internet service providers who in turn are pressed to implement networks capable of delivering bandwidths in excess of 100 Mb/s per customer. For this application, passive-optical-networks (PON) are particularly well suited as they feature lowest capital-equipment expenditures relative to point-to-point and active optical networks. The book by C. F. Lam, Passive Optical Networks: Principles and Practice, Academic Press, 2007, and publication by C-H. Lee, W. V. Sorin, and B. Y. Kim, “Fiber to the Home Using a PON Infrastructure”, IEEE J. Lightw. Technol., vol. 24, no. 12, pp. 4568-4583, 2006 give good introduction into this technology. Wavelength division multiplexing in passive optical networks (WDM-PON) is one of the actively investigated as next-generation optical network architecture. WDM-PON provides higher bandwidth per user than any other network architecture and hence potentially offers the lowest cost per unit of bandwidth to the user. However, the key difficulty in such a system has been the cost of the components, particularly arising from the need to transmit light at one wavelength for a specific channel and also receive information at any one of several other wavelengths at the user end in the so-called optical network unit (ONU). WDM optical and optoelectronic components traditionally exhibit high cost, among other issues, due to precise wavelength definitions in such systems. A dramatic cost reduction is achieved by eliminating wavelength-specific transceivers at the ONU in the colorless WDM-PON system, also referred to as a system with wavelength-agnostic transceivers in the ONU.
In a colorless optical network, the wavelengths emitted and received by the transceiver in the ONU are defined in the remote node or the central office rather than in the transceiver at the ONU as is well known in the art—see book by Lam cited above. Further reduction in complexity and cost is realized by using a a self-seeding scheme as described in a publication by E. Wong, K. L. Lee, τ. B. Anderson, “Directly Modulated Self-Seeding Reflective Semiconductor Optical Amplifiers as Colorless Transmitters in Wavelength Division Multiplexed Passive Optical Networks”, IEEE J. Lightw. Technol., vol. 25, no. 1, pp. 67-74 (2007). However, due to insufficient seeding light power and modulation present in the seeding light there have been no commercial applications of this approach.
Therefore, an unmet need for a low-cost high-performance WDM-PON solution exists in the industry. This application discloses low-cost implementations of a modulation averaging reflector that enables performance enhancement of self-seeded colorless optical networks.